Lanyard kill switch devices are safety devices well known for allowing an operator to interrupt in an emergency, for example, the operation of a working equipment. For example, a typical context of use of such known lanyard kill switch devices, and which particularly concerns the present invention, is a working equipment operatively coupled to a power source through a mechanical transmission means. Lanyard kill switch devices generally include an electrical switch assembly and a lanyard assembly. For example, the equipment is represented by a wood chipper, a log saw, or the like, operatively coupled to the power take-off (PTO) of a farm tractor through a rotating drive shaft.
The electrical switch assembly is typically attached to the power source and its output contacts are suitably electrically coupled to a control circuit thereof. The lanyard assembly includes a flexible lanyard having a first end provided with a release member adapted for releasably engaging the electrical switch assembly, and the other end attached to a portion of the working equipment. The lanyard kill switch device is thus attached between the power source and the working equipment such that the lanyard is substantially linearly stretched along a path extending transversely between a typical operating position of the operator and the mechanical transmission means.
Thus, in an emergency, the operator standing next to the rotating drive shaft only needs to pull on the lanyard in order to stop its operation. Alternatively, if the operator is wounded or falls suddenly ill and inadvertently trips on the lanyard, the power source that rotates the drive shaft is at least electrically switched off.
However, the power source and/or the working equipment, particularly the relatively old ones such as farm tractors with a power take off (PTO) and old farm equipment powered through a mechanical transmission means, generally do not have a lanyard kill switch device pre-installed by the manufacturer. The lanyard kill switch devices available on the market are generally represented by an assembly of highly customized and/or complex components, which, consequently, results in a relatively high market price and installation cost.
Furthermore, these lanyard kill switch devices are generally designed to be actuated when the release member is pulled away substantially linearly within a predetermined angle range relative to the electrical switch assembly. In other words, the lanyard attached to the release member must be sufficiently linearly stretched between the switch assembly and its anchor point on the working equipment in order to pull the release member therefrom within that predetermined angle range when a hand or limb pulls down or falls transversally across the stretched lanyard. Outside this predetermined angle range, such as when the lanyard is not stretched enough or, for some reasons, the working equipment has somehow got closer to the power source, a relatively more energetic pull down on the lanyard is required since the release member needs to be forcibly pried away at a relatively more acute angle from the switch assembly than the predetermined angle.
Thus, when the lanyard is pulled on at an angle that is outside this predetermined angle range, for example, by the back of a hand of an operator that lands softly on a loosened lanyard due to a loss of consciousness, the release member may not be pulled away from the switch assembly due to the relative acute angle value of the pull angle with respect to the switch assembly. Hence, the working equipment may continue to operate unsupervised with the ensuing safety issues that may arise from such a situation.
Against this background, there exists a need in the industry to provide an improved kill switch. An object of the present invention is therefore to provide such a kill switch.